Rotary mixer



3 Sheets-Sheet 1 v Q Job/ll .ihakq/er; Jo/m 4521485 4 I [aye/1e Purdy J. l. SPANGLER ET'AL ROTARY MIXER Filed May 31, 19-38 July 25, 1939.

M v MW ROTARY MIXER Filed May 51, 1958 3 Sheets-Sheet 2 5. I 6 0 5? [4% fine $0M; JJF.

J y A 9 J. l. SPANGLER El AL 7,3 6

ROTARY MIXER Filed May 31, 1958 s Sheets-Shet 5 Patented July 25, 1939 tfr;

' ROTARY MIXER John I. Spangler and John A. Eades,. York, Pa., and Eugene H. Purdy, Washington, D. 0., as signers to Read Machinery Company, Incorporated, York, Pa., a corporation of Pennsyl- Vania Application May31, 1938, Serial No. 211,050

14 Claims. (01. 259 -109) This invention relates to rotary mixers of the .type including an agitator. adapted to. rotate :about a horizontal axis-within a mixing chamber .in a manner such as to impart a stretching and kneading action to the plastic material contained therein.

An important objectof the invention is to pro-. vide a rotary mixer of the above character in which the agitator is provided with a plurality of rollers of different sizes equi-distantly spaced from its axis of rotation and designed to successively act upon the plastic material, such as dough, to insure'a more efiicient and uniform working of the material.

A further objectof the invention is to provide in a mixer of the above character an agitator comprising a rockably mounted pick-up member for swinging themass of plastic material from one side of the mixing chamber to the other, and a plurality of rollers of stepped sizes mounted upon the agitator and increasing in diameter in a direction opposite to the normal direction of rotation of the agitator, these rollers being adapted to roll over the material and press it against the sides and bottom ofthe mixing chamber in a manner such as to insure an active and thorough kneading thereof. I

The invention has for another object to provide a rotary mixer of the above character in ,which the pick-up member and rollers which act upon the dough are arranged so as to engage the material at approximately uniformly timed intervals in order to insure the smooth and balanced operation of the mixer, and to reduce frictional heat, such as might prove deleterious to the finished product.

Still another object of the invention is to provide a mixer of the above character in which the arms of the agitator which support the pick-up member and rollers are so constructed as to act as scrapers during their rotation for clearing away the plastic material which tends to collect adjacent the end walls of the mixing chamber and deflecting it back into the path of the pick-up member and rollers.

A further object of the invention is to provide a mixer of the above character including means whereby the axis of. rotation of the agitator may be adjusted to vary the clearance relationship of 'the rollers and pick-up member to the sides and bottom of the mixing chamber. I

Other objects and advantages will be apparent from the following detailed description of a preferred embodiment of the invention, reference being had to the annexed drawings in-which;

'Figure 1 is a view in verticaltransverse crosssection of a dough mixing machine incorporating the novel features of'the invention;

Figure 2 isa cross-sectional view of the mixer of Fig. 1 taken on the line 22 of that figure;

Figure 3 is a cross-sectional view, taken on the line 33 of Fig. 2, of one of the arms of the agitator; I

Figure 4 is a fragmentary detail View of one of the bearings for the shaft carrying the agitator;

Figure 5 is a view in vertical transverse crosssection of a modified form of mixer;

Figure 6 is a view in verticaltransverse crosssection of another modification of a mixer embodying the features of the invention; and

Figure '7 is a detail view of one of the hubs of the agitator of Fig. 6 taken on the line '!1 of that figure.

In the drawings is shown a mixer of the open trough type especially suited to the mixing and kneading of dough, although capable of use with other plastic materials. This mixer comprises a deep trough l which forms the mixing chamber in which is contained the material to be operated upon and'this trough, which is of the dump type, is rockingly supported in a stationary frame 2. Extending longitudinally through the mixing chamber and intersecting its two end walls is a rotatable shaft 3 to which is keyed for unitary rotation therewith an agitator frameor agitator--4.

- The agitator 4 comprises three pairs of arms 5, 6 and I, the arms of each pair being arranged in parallel and extending radially outward from hubs 8 encircling the shaft 3. The pairs of arms 6 and 1 are of equal length but the pair of arms 5 is of somewhat greater length than those of 6 and l. Extending between companion pairs of arms are operating members '9, l0 and II. Member 9 which extends between arms 5 consists of a swing bar having longitudinal offset ends constituting trunnions 9a rotatably journaled within openings provided in the outer ends of the pair of arms 5. V 7

Members [0 and H comprise hollow rollers of different diameters rotatably supported by the pairs of arms 6 and 1, respectively, at the outer ends of these arms. As best shown by the broken away portion of Fig. 2, each end of a roller is closed by a plug l2 having an extension I2a serving as-a trunnion which is loosely received within an opening provided in the outer end of each arm. The openings for receiving the trunnions of the rollers In and II and the swing bar 9 are each fitted with a bronze bushing [3. The arms 5, 6 and 1 are so spaced angularly about the hubs 8 that the chord distances between the rollers and between the rollers and the swing baror, otherwise stated, the distance from center to center of each of the operating members as indicated by the broken line a in Fig. l--are equal. The axes of the rollers thus travel in a common orbital path during rotation of the agitator, while the axis of oscillation of the swing bar revolves outside of such path.

In order to prevent dough from compacting against the end walls of the trough, the arms are shaped, as best indicated in Fig. 3, to function as scrapers. As shown in this figure, which is a cross-section through one of the pair of arms 5 that support the swing bar 9, the arms which travel in close proximity to the end walls of the trough are each arranged at an inclination so as to present a sharpened leading edge 14 and a fiat forward face l5 sloping away from an end wall of the trough.

For sealing the openings in the end walls of the trough through which the shaft 3 extends, packing glands It including a fibrous packing material are provided, as more clearly shown in Fig. l. A bronze wear plate 18 seats within 'a countersink in the outer end of each hub 8 and is held in place by screws 19. This wear plate is adapted to bear against a complementary wear plate 20, which likewise may be of bronze or other non-corrosive metal, closing the inner end of the packing gland. Thelatter wear plate is likewise received within a countersink on the inner face of the end wall of the trough so as to lie flush therewith and is fastened to the end wall by screws 2 I.

In the operation of the mixer just described, when motion is imparted to the shaft 3 from any suitable source of'power, the agitator 4 is rotated in the direction indicated by the arrow in Fig. 1. This causes the various operating members -to be moved through the concave bottom of the trough and into contact-with'the material confined therein. The operating members thus function initially to thoroughly mixthe ingredients constituting the batch.

After the material has attained a dough-like consistency the swing bar 9 in its revolution impacts and embeds within the plastic mass, and in its continued forward and upward movement swings the mass of dough which clings to'the swing bar from one side of the" mixing chamber to the other where it is fo-rcibly slapped against the rear wall of the trough. Subsequently the roller [0 following the swing bar rolls over the dough and imparts an initial compression thereto so as to flatten it against the rear side and bottom of the trough; then the larger roller H trailing the roller it passes over'the dough to compressit still further.

Since rolling increases the density of the dough mass, and hence the trailing roller- H encounters greater resistance than the leading roller IU, it"is necessary, in order for the mixer to perform most efiicaciously, that the roller II should be larger than the roller In so as to overcome this resistance and impart additional compression -to the dough. Such size relationship between the rollers also avoids dragging of the rollers over or through the mass of dough, which rapidly develops frictional heat. By adopting rollers of suitably large and different sized diameters and mounting them equidistantly from the axis of rotation of the agitator, a minimum amount "of power is required to rotate the agitator for the reason that there is less tendency for the material to pile up in front of and crowd over the tops of the rollers.

While the exact sizes of the rollers to be adopted will depend essentially upon the character and capacity of the mixer, a relationship which has been found to be satisfactory for the usual standard size commercial mixing machines is that in which the rollers Ill and I l are 2 inches and 5 inches in diameter, respectively, and so located with relation to the mixing chamber as to aiford a clearance of 5 inches and 3 inches, respectively, with the bottom of the trough.

Since the swing bar is free to oscillate upon its trunnions, it yields slightly upon impact with the dough and the latter is relieved from the full force of the blows delivered by the swing bar in its revolution; and because the swing bar and rollers are equidistantly spaced apart about the agitator the various operating members act at substantially uniformly timed intervals. Both of these factors conduce to a; smoother and more vibrationless operation of the mixer and to the avoidance of overheating of the dough.

During rotation of the agitator the sharpened leading edges of the pairs of arms 5, 6 and 1 cut through the mass of dough adjacent the end walls of the trough and turn this dough back toward the center of the mixing chamber.

In Fig.5 is shown a modified form of dough mixer. This'mixer corresponds generally to the mixer of Figs. 1 through 4 just described and comprises a trough constituting 'a mixing chamber through which extends in a longitudinal direction a shaft 3| carrying an agitator .32.

This agitator, like the agitator 4 .of the .mixer above described, is provided at each end with arms 33, 34, and 36 extending radially from a hub 31, and supported by companion pairs of arms are rollers 38, 39, and 4|. As indicated in the drawings, the roller 38 is of solid cross-section while the remaining rollers are hollow and of comparatively light construction.

The arms are of equal'length except the pair of arms 33 which areof somewhat greater length than the arms 34,35 and '36. Theroller 38 rotatably journaled in the ends of the pair of arms 33 is of comparatively small diameter and during the operation of the mixer is designed to function as the pick-up. member, corresponding to the swing bar 9 of the mixer of Figs. 1 through .4.

The rollers 39,40 and 4| are of stepped sizes, increasing in diameter contra to'the direction of rotation (indicated by the arrow) of the agitator. These rollers may be rotatably journaled in the outer'ends of their arms in the same manner as the rollers l0 and: II of the mixer first described. In the case of the usual standard size commercial mixers the rollers 38, 39, 40 and 4| may be of 2-inch, 3-inch, 4-inch and 5-inch diameters, respectively, and the position of the agitator with'relation to the mixing chamber such" that these rollers afford a clearance with the bottom of the trough of 2 inches, 5 inches, 4 /2 inches and 4 inches, respectively.

The arms 33 and 35, extend in alignment from diametrically opposite pointssupon the' hub 31. In order, however, that the chord distances between the centers of the rollers 38, 39, 4B and 4| be equal the arms 34 and 36 are disposed at an angle of more or less than degrees with as to cut through the dough; adjacent the end walls of the trough and turn it back toward the middle of the mixing chamber. 7

The dough mixer of Fig. 5 functions substantially the same as the mixer previously described. As the agitator rotates in the direction indicated by the'arrow in this figure, the small size pickup roller 38 acts to engage and slap the batch of dough against the rear side of the mixing trough after which the rollers 39, 40 and 4| come successively into play to pressthe dough against the sides and bottom of the trough to effect a thorough mixing and kneading of the same.

Instead of using a small size-roller, such as 'the roller 38, for the pick-up memben'a swing bar corresponding to the swing bar 9 of the mixer of Figs. 1- through 4 may be employed.

And, alternatively a small roller may be sub,

stituted for the swing bar 9 of themixer of Figs. lthrough 4 if found desirable. Where, however, a roller'serves as the pick-up bar it should be ofcomparatively small diameterin the neighborhood of .2 inchesin order to properly perform its function.-- A roller or swing'bar of small diameter has been found superior to a fixed bar, such as has been usually employed in the past as the pick-up member, for the reason that the roller or swing bar being free to turn on its trunnions is enabled .to swing the mass of dough from one side of the mixing chamber to its other without the sametendency to, tear loose from the dough as is the case with a rigidly mounted pick-up bar. v v

Illustrated in Fig. 6 in transverse cross-section is a mixer corresponding to the mixer of Figs. 1 through linsofar as comprising a trough 59 of the open-top type forming a mixing chamber, a rotatable shaft 5| extending longitudinally through the trough, and an agitator 52 carried by the [shaft and located within the mixing chamber.

end radial arms 53, 55 and 55 extending outward from a hub 56 encircling and keyed'to the shaft .5l. These arms and hubs are duplicated at opposite ends of the agitator adjacent the end walls of the mixing chamber and the arms are formed to act asscrapers in a manner which has already been explained in connection with the two before-described mixers of Figs.'1 through 5.

I, The pairs of arms. 54 and are of equal length and rotatably support rollers 5'! and 58, respectively. The trailing roller 58 mounted insthe 9 ends of the pair of arms 55 isof somewhat larger diameter'than the-leading roller 51 supported in the ends of the pair .ofarms 54. The arms 53 are longer than the-arms 54 and 55, and

the center-to center distances betweenthe two and 55' at each end ofthe agitator are not;- formed integral with the hub 56' but instead extend out from afcollar fifllwhich snuglyencir-I 51- 155 the h .Th? .1??? z j l a m n wi i a d rollers and between therollers and the'swing bar-are equal. As thus far described the mixer corresponds in all major respects to the mixer illustrated in Figs. 1 through 4;; and if desiredthe swingbar 59 may be replaced by a small size pick up roller} as described in connecti'onwith the mixer or Fig.5. V

As shown. in FigL'f'l, the series of arms 53, 54

The agitator 52, like the agitator 4 p of the first-described mixer; comprises 'at each 1 the flange and engage threaded openings in the hub.

By virtue of this construction, the clearance of the rollers and swing bar with the bottom and sides of the trough may be readily adjusted by removing the bolts 63, angularly shifting the collars 60 at opposite ends of the agitator about their eccentric hubs 56 until different threaded bolt holes come into registry with the bolt holes in the hubs and then replacing the bolts to fasten'the arms in their new positions of adjustment. Since rotation is imparted to the arms from the shaft 5 I, adjustment of'the collars about their hubs causes a bodily displacement of all the arms relative to the axis of the shaft so as to simultaneously change the positions of the swing bar and rollers relative to the trough. The opposite limit of adjustment of the arms from that shown in full lines in Fig. 6 is indicated in broken lines in the same figure. I

The operation of the mixer just described is substantially the same as that of the mixers of Figs. 1 through 5, heretofore described. Any suitable number of rollers of' stepped sizes may be adopted in conjunction with this modification,

the two rollers shown in Fig. 6 being suggestive ber and an agitator within said mixing chamber arranged for rotation about a horizontal axis,

said agitator comprising a plurality of freely rotatable rollers all of different diameters supported at equal distances from the axis of rotation of the agitator and a freely rotatable pickup member supported at a greater distance from said axis of rotation- V 2. A dough mixer comprisinga mixing cham-' ber and an agitator within said mixing chamber arranged for rotation about a horizontal axis,

said agitator comprising, a plurality ofv freely rotatable rollers of different diameters supported at equal distancesfrom the axis of rotation of the agitator, said rollers increasing in size in a direction, opposite to the normal direction. of rotation of the agitator and adaptedto successively act upon material contained in the mixing chamber and a freelyrotatable pick-up member supported at a greater distance from said axis of rotation and intermediate the rollers of small:

est and largest diameters.

3. A dough mixer comprising a mixing chamber and 'an agitator within said mixingchamber arranged for rotation about a horizontal axis,

saidagitator comprising a plurality of freely rotatable rollers of different diameters supported at equal distances from the axis "of rotation of the agitator, said rollers increasing in sizein a direction opposite to the normal direction offrotation of the agitator and adapted to succesaf sivel'y'act upon material contained in the mixing nsw e e ly ta a s p m 'r' 1 supported at a greater distance from said axis of rotation and intermediate the rollers of smallest and largest diameters, the chord distance between adjacent rollers and between the pickup member and its adjacent rollers being equal.

4. A dough mixer comprising a-mixing chamber and an agitator within said mixing chamber arranged for rotation about a horizontal axis, said agitator comprising a plurality of freely rotatable rollers of different diameters supported at equal distances from the axis of rotation of the agitator, said rollers increasing in size in a direction opposite to the normal direction of rotation of the agitator and adapted to successively act upon material contained in the mixing chamber and a freely rotatable longitudinally offset swing bar supported at a greater distance from said axis of rotation and intermediate the rollers of smallest and largest diameters.

5. A dough mixer comprising a mixing chamber and an agitator within said mixing chamber arranged for rotation about a horizontal axis, said agitator comprising a plurality of pairs of arms of equal length and a pair of arms of greater length, freely rotatable rollers all of different sizes mounted within and extending between the companion arms of equal length and a freely rotatable pick-up member mounted within and extending between the arms of greater length. V 6. A dough mixer comprising a mixing chamber and an agitator within said mixing chamber arranged for rotation about a horizontal axis, said agitator comprising a plurality of pairs of arms of equal length and a pair of arms of greater length, freely rotatable rollers all of different sizes mounted within and extending between the companion arms of equal length and a longitudinally offset swing bar rotatably mounted in and extending between the arms of greater length.

'7. A dough mixer comprising a mixing cham-,

ber and an agitator within said mixing chamber arranged for rotation about a horizontal axis,

said agitator comprising a plurality of pairs of arms of equal length and a pair of arms of greater length, freely rotatable rollers all of different sizes mounted within and extending between the companion arms of equal length and a freely rotatable pick-up roller of small diameter mounted within and extending between the arms of greater length.

8; A dough mixer comprising a mixing chamber and an agitator within said mixing chamber arranged for rotation about a horizontal axis, said agitator comnrising'a plurality of pairs of arms of equal length and a pair of arms of greater length, freely rotatable rollers all of increasing size mounted within and extending between the companion arms of equal length adapted to successivelyact upon material con-' mixing chamber and a freely rotatable longiamen-e tudinallyoffset swing bar extending between the arms of greater length and located intermediate the rollers of smallest and greatest diameter.

Q 10. A dough mixer comprising a mixing chamber and an agitator within said mixing chamber arranged for rotation about a horizontal axis, said agitator comprising a plurality of pairs of arms of equal length, and a pair of arms of greater length, freely rotatable rollers all of different sizes mounted within and extending between the companion arms of equal length, a freely rotatable pick-up member extending between the arms of greater length, hubs eccentrically disposed relative to the axis of rotation of the agitator, collars surrounding the hubs and united with the inner ends of the arms at opposite ends of the agitator and detachable means connecting said collars to the hubs but permitting angular adjustment of the collars relative thereto.

11. The combination with a mixer of the type comprising a mixing chamber, an agitator within said mixing chamber having a plurality of longitudinally-extending operating elements and shafts supporting said agitator at its ends for rotation within said mixing chamber, of means for varying the clearance between. the operating elements and the wall of the mixing chamber, said means comprising hubs eccentrically mounted on the shafts adjacent the ends of the agitator for rotation with said shafts and supporting means for the operating elements detachably connected to the hubs and adjustable angularly to different positions thereabout.

12. The combination with a mixer of the type comprising a mixing chamber, an agitator within said mixing chamber having a plurality of longitudinally-extending operating elements and shafts supporting said agitator at its ends for rotation within said mixing chamber, of means for varying the clearance between the operating elements and the wall of the mixing chamber, said means comprising cylindrical hubs eccentrically mounted on the shafts adjacent the ends of the agitator for rotation with said shafts, collars encircling said hubs, arms extending outward from said collars and supporting the operating elements and means detachably connecting the collars to the hubs to permit rotation of the collars about the hubs to different positions of adjustment.

13. The combination with a mixer of the type comprising a mixing chamber, an agitator within said mixing chamber having a plurality of longitudinally-extending operating elements and shafts supporting said agitator at its ends for rotation within said mixing chamber, of means for varying the clearance between the operating elements and the wall of the mixing chamber, said means comprising cylindrical hubs eccentrically mounted on the shafts for rotation therewith, collars surrounding said hubs, arms extending outward from said collars and arranged in pairs at opposite ends of the agitator for supporting the operating elements therebetween, a plurality of pairs of said arms being of substantially equal length. 7 v

14. The combination with a mixer of the type comprising a mixing chamber, an agitator rotat- V able within said mixing chamber including a plurality of longitudinally-extending rollers of stepped sizes and all increasing in size in a direction opposite to the normal direction of rotation of the agitator, and shafts'supporting said agitator at its ends for rotation, of means for Varying the clearanoe between the rollers and the wall of the mixing chamber, said means comprising cylindrical hubs eccentrically mounted on the shafts adjacent the ends of the agitator for rotation with said shafts, collars encircling said hubs, arms of substantially equal length extending outward from said collars and arranged in pairs at opposite ends of the agitator for supporting the rollers therebetween.

JOHN I. SPANGLER. JOHN A. EADES. EUGENE H. PURDY. 

